A moss plant can not complete its life cycle in dry condition because of following two main reasons :
(i) It requires water for the dehiscence of antheridium the male sex organ and the opening of the archegonium-the female sex organ.
(ii) It requires the presence of water for the flagellated antherozoids (the male gametes) to swim and reach the female gamete (egg or ovum) situated deep in the archegonium under the influence of a chemical (maleic acid), accomplishing fertilization
